1. Field of the Invention
This invention relates to a vehicle steering and operating apparatus used mainly for motor graders and which enables positions and attitudes of a steering wheel and operating levers thereof to be varied in the longitudinal and vertical directions of the vehicle.
2. Description of the Prior Art
In driving a motor grader, its operator assumes both standing and seated postures depending on the nature of the work to be carried out. At that time, it is desirable for the operator to move the steering wheel and the operating levers in the longitudinal and vertical directions in accordance with his postures.
The above-mentioned conventional vehicle steering and operating apparatus is arranged such that, as can be seen from FIG. 7, a main column "b" having a steering wheel "a" attached to the uppermost part thereof is mounted on a floor plate "c" in such a manner that it can be tilted relative to the floor plate in the longitudinal direction of the vehicle, and a plurality of operating levers "d" are carried by the main column "b" and arranged such that they can be tilted together with the main column "b" in the longitudinal direction of the vehicle.
Besides the above-mentioned prior art example, there is another vehicle steering and operating apparatus disclosed in the Japanese Patent Publication No. 57-41082.
The vehicle steering and operating apparatus shown in this publicly known embodiment is arranged such that both the steering wheel and the operating levers group can be moved in substantially parallel relationship with their original positions at the same attitude, while the main column can be tilted in the longitudinal direction of the vehicle.
The above-mentioned former prior art former embodiment has been disadvantageous in that, when the main column "b" is tilted backwards as shown by phantom lines in FIG. 7, the steering wheel "a" and the operating levers "d" are tilted backwards at the same attitude as the main column "b" so that their attitudes are set indiscriminately by the angle of inclination of the main column "b" thus making it impossible for the operator to adjust their attitudes in accordance with the body build of the operator and the nature of the work to be carried out.
Further, the above-mentioned prior art letter embodiment has been disadvantageous in that, while the steering wheel and the operating levers can be held at the same attitude regardless of the inclination angle of the main column, the attitudes of the steering wheel and the operating levers cannot be changed independently from each other in accordance with their heights from the floor plate and their positions in the longitudinal direction of the vehicle, thus making it impossible to adjust their attitudes according to the body build of the operator and the work to be conducted as in the case of the prior art former embodiment.